U.S. President Donald Trump said Tuesday that his administration was aware of undeclared North Korean missile bases revealed by U.S. researchers.

Trump wrote on Twitter that the story in the New York Times concerning North Korea developing missile bases is "inaccurate," calling it "just more fake news."

He said the U.S. fully knows about the sites being discussed, and there were nothing out of the normal happening, adding he will be the first to reveal if things go bad. 

Researchers at the Center for Strategic and International Studies, a prominent Washington think tank, said on Monday that satellite imagery had found 13 missile bases undeclared by North Korea.

The New York Times reported that the satellite images suggest that the North has been engaged in a great deception as it has offered to dismantle a major launching site while continuing to make improvements at more than a dozen others that would bolster launches of conventional and nuclear warheads.